Looking for a way to create details fabric texture(Normal Map)
For this kind of object you will necessarily have seams somewhere but you could delete the one on the top and it will unwrap correctly. You could also model a seam at the top so that it matches the UV seam.
As for the material, you could use a real picture of wool, but if you want to stay procedural, you can improve what you've done so far with some tweakings:

For the moment your wool looks a bit plastic, it is not supposed to be so glossy, so increase the Roughness and decrease the Specular values.
To make its tint more realistic and less monochromatic, Plug a Noise Texture node (with a high Scale value) into a ColorRamp with 2 or more colors.



About your question on mixing 2 normal maps, you can do it through a MixRGB, then plug the MixRGB into a Converter &gt; Vector Math &gt; Normalize:

I've watched this method that recommends to separate and recombine the RGB channels but I can't see any difference with my method as soon as I put a Converter &gt; Vector Math &gt; Normalize node as well, maybe node experts will tell...